Maarten Van Steenberge, Noemie Jublier, Loic Kever, Sophie Gresham, Sofie Derycke, Jos Snoeks, Eric Parmentier, Pascal Poncin, Erik VerheyenPlease use the format "First name initials family name" as in "Marie S. Curie, Niels H. D. Bohr, Albert Einstein, John R. R. Tolkien, Donna T. Strickland"
<p style="text-align: justify;">Cichlid radiations often harbour closely related species with overlapping niches and distribution ranges. Such species sometimes hybridise in nature, which raises the question how can they coexist. This also holds for the Tanganyika mouthbrooders <em>Ophthalmotilapia ventralis</em> and <em>O. nasuta</em>. Earlier studies found indications of asymmetrical hybridisation with females of <em>O. ventralis</em> accepting males of <em>O. nasuta</em>, but not the other way around. We hypothesised that this was due to differences in the capacity for species recognition. Given the higher propensity of <em>O. ventralis</em> females towards hybridisation, we expect a reduced ability for species recognition in <em>O. ventralis</em> females, compared to <em>O. nasuta</em> females. We staged two experiments, one focusing on 22 female <em>O. nasuta</em> and one on 21 female <em>O. ventralis</em>. These fish were placed in one half of a tank and briefly exposed to a conspecific or a heterospecific male, a conspecific female, or nothing (control). Female response was evaluated by scoring six tracking parameters and by noting the occurrence of ten discrete behaviours before and during the encounter. Females always responded to the presence of another fish by approaching it. Remarkably, for both <em>O. nasuta</em> and <em>O. ventralis</em>, we did not find a different response between encounters with conspecific males and females. However, in agreement with our hypothesis, <em>O. nasuta</em> females behaved differently towards conspecific or heterospecific males, whereas <em>O. ventralis</em> females did not. When presented with a heterospecific male, <em>O. nasuta</em> females performed a lower number of ‘ram’ behaviours. Additionally, they never displayed the ‘flee’ behaviour, a component of the species’ mating repertoire that was seen in all but one of the presentations with a conspecific male. Our findings show that differences in species recognition at first encounter predict to a large degree the outcome of the mating process, even in the absence of mating behaviour. </p>
Species recognition, mate choice, behaviour, Lake Tanganyika, Africa
Aquatic, Behavior, Evolution, Fish, Vertebrates, Veterinary entomology